Novel thiourea derivatives of α-amino acids and their oxorhenium(V) complexes

N-[(Dialkylamino)(thiocarbonyl)]benzimidoyl chlorides react with α-amino acid esters under formation of the corresponding N-[(dialkylamino)(thiocarbonyl)]benzamidines. Derivatives with glycine ethylester, HL(GlyOEt), cysteine methylester and S-benzyl protected cysteine ethylester, HL(S-Bzl-CysOEt), were prepared and isolated in crystalline form. The reaction with cysteine methylester yields the corresponding sulfur-bridged dimeric compound {HL(CysOMe)}2.Starting from [ReOCl3(PPh3)2], complexes of these new ligands could be obtained in two different coordination modes: monodentate coordination by only the thiourea sulfur atom or S,N,O tridentate coordination after ester hydrolysis.

Graphical abstractNovel benzamidines prepared from N-[(dialkylamino)(thiocarbonyl)]benzimidoyl chlorides and α-amino acid esters react with [ReOCl3(PPh3)2] as monodentate or tridentate ligands depending on the reaction conditions applied. Metal-supported ester hydrolysis and the formation of the tridentate ligands is achieved under mild conditions.Figure optionsDownload full-size imageDownload as PowerPoint slide